John feeaesqn



J'. FREARSON. SCREW-DRIVER.

No.179,695. Patented J'u1y11,187-6.

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Specification forming part. or Lam-re uest. 179,606, July 11, 1816;appllostion filed i March 23, 1876. p

provements in screw-drivers is applicable.

My invention in screw-drivers consists of the improvements hereinafterdescribed, and illustrated in the accompanying drawings.

Beforedescribing my said invention it] screwdrivers I may remark, by wayoi'contrast, that the termination erecting end of the. ordinary"screwdriver is of a rectangular-figure, so as to fit the rectangulargroove or nick which extends across the head of the ordinary screw.

To this kind of screw and-screwdriver there are many well-knownobjections, some of which -I. will-mention. For instance. when thescrewdriver properly fits the width and whole length of the said grooveor nick in the hea. of one size of the ordinary screw it will notproperly fit any other size, because the blade of the screw-driverwillnot extend to the whole 7 length of the grooves of screws of a largersize,

and therefore there will be a loss of the requisite power to drive suchlarger-sized screws,

and the said screw-driver will extend beyond.

the heads of screws of smaller size, so that the two edges of the actingend of the driver, protruding beyond the heads of smaller screws, comein contaet'with the countersunk material, so as to disfigure the work,and the protruding edges of the screw-driver prevent the screw frombeing driven to its required position. When the said screw-driver isground taper on its two flat sides, for the purpose of driving screws ofdifferent sizes, there is a tendency for the driver to slip out of thegroove or nick in the act of driving the screw, and also to deface thefinished work. As the ordinary screw-heads are upset by a flat-faced dieor punch, the heads are generally fractured, and,

when the nick happens to be in one of these is in the center of the headof the screw.

lractures the tendency is to burst the head. asunder. V a

Now, the object of my invention in screws: and screw-drivers is toremove or diminish all the before-mentioned objections, and Ieffectually remove or diminish the said objections in the followingmanner:

By reference to the specification of my petcavity isot' a'combined Vshape-that is, its

sides and its: ends all inclinemr converge to or toward one point;thereforeits greatest depfh n another head of a screw there are two Vcavities or nicks crossing each other at right angles at the center ofthe screw-head, thus forming four radial grooves or nicks' and inanother head of a screw there are three V-nicks crossing each other atthe center of the screwhead, thus forming six radial grooves or nicks,each making, with the adjacent one, an angle of about sixty degrees.Each crossing nick in the two last-mentioned screws are of precisely thesame angles as the single one first described.

My invention of improvements in screwdrivers is applicable to the saidscrews.

The screw-driver, which is applicable to the said single nick in thehead of my screw, or to any one of the combined V-nicks, has a flatblade, its acting end being of a combined V shape.

The other screw-drivers, which are applicable to those of the screwswhich contain sev-' eral V-nicks, have several radial V-branches, allconverging to or toward one point. In making these screw-drivers I firstmake that part which is to enter the cavity in the head of the screw ot'a conical shape, and then, by means of cutting-tools or other means, Imake three or more flutes or grooves in the said conical part, thusleaving a corresponding number of radial V-branches, the three sides .ofeach branch from the base'to the apex of the cone converging to ortoward one point.

I will now describe my invention with reference to the accompanyingdrawings.

A, Figure 1. represents in elevation the broad side, and A, Fig. 2,reprcsentsiu elevation the narrow side, and A, Fig.3, represents in planthe acting end, of a screw-driver according to my invention. Fig. irepresents, in elevation, the acting end of a screw-driver which hasthree radial V- branches, each marked B, and all the said branches, fromthe base to the apex of the fluted cone, converge to or toward onepoint; and Fig. 5 is a plan of the same. This screw-driver is applicableto a screw-head having three or six radial V- grooves therein. Fig. 6represents, in elevation, the acting end of a screwdriver which has fourradial V-branches, which are at right' angles to each other, and eachmarked B, and

' all the said branches, which form the fluted cone, incline or convergeto ortoward one point; and Fig. 7 is aplan of the same. Thisscrew-driver is applicable to the cavities in the heads of screws havingtwo V-nicks crossing each other in the center of the heads.

By preference I make the screw-driver of the last description asillustrated, Figs.6 and 7; and as the cavities in the heads of my screwswill be made to correspond with the acting ends of the saidscrew-drivers, the angles being the same in all sizes of screws andscrew-drivers, every size of screw can be driven by one screwdriver,each sizeof screw possessing a cavity exactly proportionate to its sizeand the power required to driveit. As the cavities in the heads of mypatent screws are deepest in the center, and of great depth,

the screw-driver takes a firmer gripe of the screw than the ordinarydriver takes in the nicks of the ordinary kinds. The screw-driver,according to my invention, at once takes its axial position, and whenpressed in the cavity as the ordinary driver is pressed it cannot slipout of the cavity so as to deface the work; and as the cavities do notextend to the sides of the screw-head, the screw-head is much strongerthan that of the ordinary kind, and from the construction of the driverand the cavity the driver can never come in contact with the countersunkportion of the work.

I make, by preference, the angle marked A, Fig. 1, of about thirtydegrees, and the angle marked A, Fig. 2, of about ten or twelve degrees.7

Having describedmy invention, and the manner it may be performed, I wishit to be understood that I do not confine myself to the precise detailsherein described and illustrated, as the same'may be varied withoutdeparting from the;nature of myinvention; but

I claim as my invention of improvementsin screw-drivers- A screw-driverhaving two or more radial branches extending from the centeror axis,

and describinga cone in revolving, all the acts i'ng'sides of the saidradial branches converging toward an axial point, substantially as andfor the purposes described, and as illustrated in the accompanyingdrawings.

JOHN FREARSON. Witnesses: 7

.J 01am B. GOULD, J. FRANCIS BRAME.

